<?php
/**
 * Zend Framework
 *
 * LICENSE
 *
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 *
 * @category   Zend
 * @package    Zend_Auth
 * @subpackage Zend_Auth_Adapter_Http
 * @copyright  Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 * @version    $Id: Http.php 18951 2009-11-12 16:26:19Z alexander $
 */


/**
 * @see Zend_Auth_Adapter_Interface
 */
require_once 'Zend/Auth/Adapter/Interface.php';


/**
 * HTTP Authentication Adapter
 *
 * Implements a pretty good chunk of RFC 2617.
 *
 * @category   Zend
 * @package    Zend_Auth
 * @subpackage Zend_Auth_Adapter_Http
 * @copyright  Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 * @todo       Support auth-int
 * @todo       Track nonces, nonce-count, opaque for replay protection and stale support
 * @todo       Support Authentication-Info header
 */
class Zend_Auth_Adapter_Http implements Zend_Auth_Adapter_Interface
{
	/**
	 * Reference to the HTTP Request object
	 *
	 * @var Zend_Controller_Request_Http
	 */
	protected $_request;

	/**
	 * Reference to the HTTP Response object
	 *
	 * @var Zend_Controller_Response_Http
	 */
	protected $_response;

	/**
	 * Object that looks up user credentials for the Basic scheme
	 *
	 * @var Zend_Auth_Adapter_Http_Resolver_Interface
	 */
	protected $_basicResolver;

	/**
	 * Object that looks up user credentials for the Digest scheme
	 *
	 * @var Zend_Auth_Adapter_Http_Resolver_Interface
	 */
	protected $_digestResolver;

	/**
	 * List of authentication schemes supported by this class
	 *
	 * @var array
	 */
	protected $_supportedSchemes = array('basic', 'digest');

	/**
	 * List of schemes this class will accept from the client
	 *
	 * @var array
	 */
	protected $_acceptSchemes;

	/**
	 * Space-delimited list of protected domains for Digest Auth
	 *
	 * @var string
	 */
	protected $_domains;

	/**
	 * The protection realm to use
	 *
	 * @var string
	 */
	protected $_realm;

	/**
	 * Nonce timeout period
	 *
	 * @var integer
	 */
	protected $_nonceTimeout;

	/**
	 * Whether to send the opaque value in the header. True by default
	 *
	 * @var boolean
	 */
	protected $_useOpaque;

	/**
	 * List of the supported digest algorithms. I want to support both MD5 and
	 * MD5-sess, but MD5-sess won't make it into the first version.
	 *
	 * @var array
	 */
	protected $_supportedAlgos = array('MD5');

	/**
	 * The actual algorithm to use. Defaults to MD5
	 *
	 * @var string
	 */
	protected $_algo;

	/**
	 * List of supported qop options. My intetion is to support both 'auth' and
	 * 'auth-int', but 'auth-int' won't make it into the first version.
	 *
	 * @var array
	 */
	protected $_supportedQops = array('auth');

	/**
	 * Whether or not to do Proxy Authentication instead of origin server
	 * authentication (send 407's instead of 401's). Off by default.
	 *
	 * @var boolean
	 */
	protected $_imaProxy;

	/**
	 * Flag indicating the client is IE and didn't bother to return the opaque string
	 *
	 * @var boolean
	 */
	protected $_ieNoOpaque;

	/**
	 * Constructor
	 *
	 * @param  array $config Configuration settings:
	 *    'accept_schemes' => 'basic'|'digest'|'basic digest'
	 *    'realm' => <string>
	 *    'digest_domains' => <string> Space-delimited list of URIs
	 *    'nonce_timeout' => <int>
	 *    'use_opaque' => <bool> Whether to send the opaque value in the header
	 *    'alogrithm' => <string> See $_supportedAlgos. Default: MD5
	 *    'proxy_auth' => <bool> Whether to do authentication as a Proxy
	 * @throws Zend_Auth_Adapter_Exception
	 * @return void
	 */
	public function __construct(array $config)
	{
		if (!extension_loaded('hash')) {
			/**
			 * @see Zend_Auth_Adapter_Exception
			 */
			require_once 'Zend/Auth/Adapter/Exception.php';
			throw new Zend_Auth_Adapter_Exception(__CLASS__  . ' requires the \'hash\' extension');
		}

		$this->_request  = null;
		$this->_response = null;
		$this->_ieNoOpaque = false;


		if (empty($config['accept_schemes'])) {
			/**
			 * @see Zend_Auth_Adapter_Exception
			 */
			require_once 'Zend/Auth/Adapter/Exception.php';
			throw new Zend_Auth_Adapter_Exception('Config key \'accept_schemes\' is required');
		}

		$schemes = explode(' ', $config['accept_schemes']);
		$this->_acceptSchemes = array_intersect($schemes, $this->_supportedSchemes);
		if (empty($this->_acceptSchemes)) {
			/**
			 * @see Zend_Auth_Adapter_Exception
			 */
			require_once 'Zend/Auth/Adapter/Exception.php';
			throw new Zend_Auth_Adapter_Exception('No supported schemes given in \'accept_schemes\'. Valid values: '
			. implode(', ', $this->_supportedSchemes));
		}

		// Double-quotes are used to delimit the realm string in the HTTP header,
		// and colons are field delimiters in the password file.
		if (empty($config['realm']) ||
		!ctype_print($config['realm']) ||
		strpos($config['realm'], ':') !== false ||
		strpos($config['realm'], '"') !== false) {
			/**
			 * @see Zend_Auth_Adapter_Exception
			 */
			require_once 'Zend/Auth/Adapter/Exception.php';
			throw new Zend_Auth_Adapter_Exception('Config key \'realm\' is required, and must contain only printable '
			. 'characters, excluding quotation marks and colons');
		} else {
			$this->_realm = $config['realm'];
		}

		if (in_array('digest', $this->_acceptSchemes)) {
			if (empty($config['digest_domains']) ||
			!ctype_print($config['digest_domains']) ||
			strpos($config['digest_domains'], '"') !== false) {
				/**
				 * @see Zend_Auth_Adapter_Exception
				 */
				require_once 'Zend/Auth/Adapter/Exception.php';
				throw new Zend_Auth_Adapter_Exception('Config key \'digest_domains\' is required, and must contain '
				. 'only printable characters, excluding quotation marks');
			} else {
				$this->_domains = $config['digest_domains'];
			}

			if (empty($config['nonce_timeout']) ||
			!is_numeric($config['nonce_timeout'])) {
				/**
				 * @see Zend_Auth_Adapter_Exception
				 */
				require_once 'Zend/Auth/Adapter/Exception.php';
				throw new Zend_Auth_Adapter_Exception('Config key \'nonce_timeout\' is required, and must be an '
				. 'integer');
			} else {
				$this->_nonceTimeout = (int) $config['nonce_timeout'];
			}

			// We use the opaque value unless explicitly told not to
			if (isset($config['use_opaque']) && false == (bool) $config['use_opaque']) {
				$this->_useOpaque = false;
			} else {
				$this->_useOpaque = true;
			}

			if (isset($config['algorithm']) && in_array($config['algorithm'], $this->_supportedAlgos)) {
				$this->_algo = $config['algorithm'];
			} else {
				$this->_algo = 'MD5';
			}
		}

		// Don't be a proxy unless explicitly told to do so
		if (isset($config['proxy_auth']) && true == (bool) $config['proxy_auth']) {
			$this->_imaProxy = true;  // I'm a Proxy
		} else {
			$this->_imaProxy = false;
		}
	}

	/**
	 * Setter for the _basicResolver property
	 *
	 * @param  Zend_Auth_Adapter_Http_Resolver_Interface $resolver
	 * @return Zend_Auth_Adapter_Http Provides a fluent interface
	 */
	public function setBasicResolver(Zend_Auth_Adapter_Http_Resolver_Interface $resolver)
	{
		$this->_basicResolver = $resolver;

		return $this;
	}

	/**
	 * Getter for the _basicResolver property
	 *
	 * @return Zend_Auth_Adapter_Http_Resolver_Interface
	 */
	public function getBasicResolver()
	{
		return $this->_basicResolver;
	}

	/**
	 * Setter for the _digestResolver property
	 *
	 * @param  Zend_Auth_Adapter_Http_Resolver_Interface $resolver
	 * @return Zend_Auth_Adapter_Http Provides a fluent interface
	 */
	public function setDigestResolver(Zend_Auth_Adapter_Http_Resolver_Interface $resolver)
	{
		$this->_digestResolver = $resolver;

		return $this;
	}

	/**
	 * Getter for the _digestResolver property
	 *
	 * @return Zend_Auth_Adapter_Http_Resolver_Interface
	 */
	public function getDigestResolver()
	{
		return $this->_digestResolver;
	}

	/**
	 * Setter for the Request object
	 *
	 * @param  Zend_Controller_Request_Http $request
	 * @return Zend_Auth_Adapter_Http Provides a fluent interface
	 */
	public function setRequest(Zend_Controller_Request_Http $request)
	{
		$this->_request = $request;

		return $this;
	}

	/**
	 * Getter for the Request object
	 *
	 * @return Zend_Controller_Request_Http
	 */
	public function getRequest()
	{
		return $this->_request;
	}

	/**
	 * Setter for the Response object
	 *
	 * @param  Zend_Controller_Response_Http $response
	 * @return Zend_Auth_Adapter_Http Provides a fluent interface
	 */
	public function setResponse(Zend_Controller_Response_Http $response)
	{
		$this->_response = $response;

		return $this;
	}

	/**
	 * Getter for the Response object
	 *
	 * @return Zend_Controller_Response_Http
	 */
	public function getResponse()
	{
		return $this->_response;
	}

	/**
	 * Authenticate
	 *
	 * @throws Zend_Auth_Adapter_Exception
	 * @return Zend_Auth_Result
	 */
	public function authenticate()
	{
		if (empty($this->_request) ||
		empty($this->_response)) {
			/**
			 * @see Zend_Auth_Adapter_Exception
			 */
			require_once 'Zend/Auth/Adapter/Exception.php';
			throw new Zend_Auth_Adapter_Exception('Request and Response objects must be set before calling '
			. 'authenticate()');
		}

		if ($this->_imaProxy) {
			$getHeader = 'Proxy-Authorization';
		} else {
			$getHeader = 'Authorization';
		}

		$authHeader = $this->_request->getHeader($getHeader);
		if (!$authHeader) {
			return $this->_challengeClient();
		}

		list($clientScheme) = explode(' ', $authHeader);
		$clientScheme = strtolower($clientScheme);

		// The server can issue multiple challenges, but the client should
		// answer with only the selected auth scheme.
		if (!in_array($clientScheme, $this->_supportedSchemes)) {
			$this->_response->setHttpResponseCode(400);
			return new Zend_Auth_Result(
			Zend_Auth_Result::FAILURE_UNCATEGORIZED,
			array(),
			array('Client requested an incorrect or unsupported authentication scheme')
			);
		}

		// client sent a scheme that is not the one required
		if (!in_array($clientScheme, $this->_acceptSchemes)) {
			// challenge again the client
			return $this->_challengeClient();
		}

		switch ($clientScheme) {
			case 'basic':
				$result = $this->_basicAuth($authHeader);
				break;
			case 'digest':
				$result = $this->_digestAuth($authHeader);
				break;
			default:
				/**
				 * @see Zend_Auth_Adapter_Exception
				 */
				require_once 'Zend/Auth/Adapter/Exception.php';
				throw new Zend_Auth_Adapter_Exception('Unsupported authentication scheme');
		}

		return $result;
	}

	/**
	 * Challenge Client
	 *
	 * Sets a 401 or 407 Unauthorized response code, and creates the
	 * appropriate Authenticate header(s) to prompt for credentials.
	 *
	 * @return Zend_Auth_Result Always returns a non-identity Auth result
	 */
	protected function _challengeClient()
	{
		if ($this->_imaProxy) {
			$statusCode = 407;
			$headerName = 'Proxy-Authenticate';
		} else {
			$statusCode = 401;
			$headerName = 'WWW-Authenticate';
		}

		$this->_response->setHttpResponseCode($statusCode);

		// Send a challenge in each acceptable authentication scheme
		if (in_array('basic', $this->_acceptSchemes)) {
			$this->_response->setHeader($headerName, $this->_basicHeader());
		}
		if (in_array('digest', $this->_acceptSchemes)) {
			$this->_response->setHeader($headerName, $this->_digestHeader());
		}
		return new Zend_Auth_Result(
		Zend_Auth_Result::FAILURE_CREDENTIAL_INVALID,
		array(),
		array('Invalid or absent credentials; challenging client')
		);
	}

	/**
	 * Basic Header
	 *
	 * Generates a Proxy- or WWW-Authenticate header value in the Basic
	 * authentication scheme.
	 *
	 * @return string Authenticate header value
	 */
	protected function _basicHeader()
	{
		return 'Basic realm="' . $this->_realm . '"';
	}

	/**
	 * Digest Header
	 *
	 * Generates a Proxy- or WWW-Authenticate header value in the Digest
	 * authentication scheme.
	 *
	 * @return string Authenticate header value
	 */
	protected function _digestHeader()
	{
		$wwwauth = 'Digest realm="' . $this->_realm . '", '
		. 'domain="' . $this->_domains . '", '
		. 'nonce="' . $this->_calcNonce() . '", '
		. ($this->_useOpaque ? 'opaque="' . $this->_calcOpaque() . '", ' : '')
		. 'algorithm="' . $this->_algo . '", '
		. 'qop="' . implode(',', $this->_supportedQops) . '"';

		return $wwwauth;
	}

	/**
	 * Basic Authentication
	 *
	 * @param  string $header Client's Authorization header
	 * @throws Zend_Auth_Adapter_Exception
	 * @return Zend_Auth_Result
	 */
	protected function _basicAuth($header)
	{
		if (empty($header)) {
			/**
			 * @see Zend_Auth_Adapter_Exception
			 */
			require_once 'Zend/Auth/Adapter/Exception.php';
			throw new Zend_Auth_Adapter_Exception('The value of the client Authorization header is required');
		}
		if (empty($this->_basicResolver)) {
			/**
			 * @see Zend_Auth_Adapter_Exception
			 */
			require_once 'Zend/Auth/Adapter/Exception.php';
			throw new Zend_Auth_Adapter_Exception('A basicResolver object must be set before doing Basic '
			. 'authentication');
		}

		// Decode the Authorization header
		$auth = substr($header, strlen('Basic '));
		$auth = base64_decode($auth);
		if (!$auth) {
			/**
			 * @see Zend_Auth_Adapter_Exception
			 */
			require_once 'Zend/Auth/Adapter/Exception.php';
			throw new Zend_Auth_Adapter_Exception('Unable to base64_decode Authorization header value');
		}

		// See ZF-1253. Validate the credentials the same way the digest
		// implementation does. If invalid credentials are detected,
		// re-challenge the client.
		if (!ctype_print($auth)) {
			return $this->_challengeClient();
		}
		// Fix for ZF-1515: Now re-challenges on empty username or password
		$creds = array_filter(explode(':', $auth));
		if (count($creds) != 2) {
			return $this->_challengeClient();
		}

		$password = $this->_basicResolver->resolve($creds[0], $this->_realm);
		if ($password && $password == $creds[1]) {
			$identity = array('username'=>$creds[0], 'realm'=>$this->_realm);
			return new Zend_Auth_Result(Zend_Auth_Result::SUCCESS, $identity);
		} else {
			return $this->_challengeClient();
		}
	}

	/**
	 * Digest Authentication
	 *
	 * @param  string $header Client's Authorization header
	 * @throws Zend_Auth_Adapter_Exception
	 * @return Zend_Auth_Result Valid auth result only on successful auth
	 */
	protected function _digestAuth($header)
	{
		if (empty($header)) {
			/**
			 * @see Zend_Auth_Adapter_Exception
			 */
			require_once 'Zend/Auth/Adapter/Exception.php';
			throw new Zend_Auth_Adapter_Exception('The value of the client Authorization header is required');
		}
		if (empty($this->_digestResolver)) {
			/**
			 * @see Zend_Auth_Adapter_Exception
			 */
			require_once 'Zend/Auth/Adapter/Exception.php';
			throw new Zend_Auth_Adapter_Exception('A digestResolver object must be set before doing Digest authentication');
		}

		$data = $this->_parseDigestAuth($header);
		if ($data === false) {
			$this->_response->setHttpResponseCode(400);
			return new Zend_Auth_Result(
			Zend_Auth_Result::FAILURE_UNCATEGORIZED,
			array(),
			array('Invalid Authorization header format')
			);
		}

		// See ZF-1052. This code was a bit too unforgiving of invalid
		// usernames. Now, if the username is bad, we re-challenge the client.
		if ('::invalid::' == $data['username']) {
			return $this->_challengeClient();
		}

		// Verify that the client sent back the same nonce
		if ($this->_calcNonce() != $data['nonce']) {
			return $this->_challengeClient();
		}
		// The opaque value is also required to match, but of course IE doesn't
		// play ball.
		if (!$this->_ieNoOpaque && $this->_calcOpaque() != $data['opaque']) {
			return $this->_challengeClient();
		}

		// Look up the user's password hash. If not found, deny access.
		// This makes no assumptions about how the password hash was
		// constructed beyond that it must have been built in such a way as
		// to be recreatable with the current settings of this object.
		$ha1 = $this->_digestResolver->resolve($data['username'], $data['realm']);
		if ($ha1 === false) {
			return $this->_challengeClient();
		}

		// If MD5-sess is used, a1 value is made of the user's password
		// hash with the server and client nonce appended, separated by
		// colons.
		if ($this->_algo == 'MD5-sess') {
			$ha1 = hash('md5', $ha1 . ':' . $data['nonce'] . ':' . $data['cnonce']);
		}

		// Calculate h(a2). The value of this hash depends on the qop
		// option selected by the client and the supported hash functions
		switch ($data['qop']) {
			case 'auth':
				$a2 = $this->_request->getMethod() . ':' . $data['uri'];
				break;
			case 'auth-int':
				// Should be REQUEST_METHOD . ':' . uri . ':' . hash(entity-body),
				// but this isn't supported yet, so fall through to default case
			default:
				/**
				 * @see Zend_Auth_Adapter_Exception
				 */
				require_once 'Zend/Auth/Adapter/Exception.php';
				throw new Zend_Auth_Adapter_Exception('Client requested an unsupported qop option');
		}
		// Using hash() should make parameterizing the hash algorithm
		// easier
		$ha2 = hash('md5', $a2);


		// Calculate the server's version of the request-digest. This must
		// match $data['response']. See RFC 2617, section 3.2.2.1
		$message = $data['nonce'] . ':' . $data['nc'] . ':' . $data['cnonce'] . ':' . $data['qop'] . ':' . $ha2;
		$digest  = hash('md5', $ha1 . ':' . $message);

		// If our digest matches the client's let them in, otherwise return
		// a 401 code and exit to prevent access to the protected resource.
		if ($digest == $data['response']) {
			$identity = array('username'=>$data['username'], 'realm'=>$data['realm']);
			return new Zend_Auth_Result(Zend_Auth_Result::SUCCESS, $identity);
		} else {
			return $this->_challengeClient();
		}
	}

	/**
	 * Calculate Nonce
	 *
	 * @return string The nonce value
	 */
	protected function _calcNonce()
	{
		// Once subtle consequence of this timeout calculation is that it
		// actually divides all of time into _nonceTimeout-sized sections, such
		// that the value of timeout is the point in time of the next
		// approaching "boundary" of a section. This allows the server to
		// consistently generate the same timeout (and hence the same nonce
		// value) across requests, but only as long as one of those
		// "boundaries" is not crossed between requests. If that happens, the
		// nonce will change on its own, and effectively log the user out. This
		// would be surprising if the user just logged in.
		$timeout = ceil(time() / $this->_nonceTimeout) * $this->_nonceTimeout;

		$nonce = hash('md5', $timeout . ':' . $this->_request->getServer('HTTP_USER_AGENT') . ':' . __CLASS__);
		return $nonce;
	}

	/**
	 * Calculate Opaque
	 *
	 * The opaque string can be anything; the client must return it exactly as
	 * it was sent. It may be useful to store data in this string in some
	 * applications. Ideally, a new value for this would be generated each time
	 * a WWW-Authenticate header is sent (in order to reduce predictability),
	 * but we would have to be able to create the same exact value across at
	 * least two separate requests from the same client.
	 *
	 * @return string The opaque value
	 */
	protected function _calcOpaque()
	{
		return hash('md5', 'Opaque Data:' . __CLASS__);
	}

	/**
	 * Parse Digest Authorization header
	 *
	 * @param  string $header Client's Authorization: HTTP header
	 * @return array|false Data elements from header, or false if any part of
	 *         the header is invalid
	 */
	protected function _parseDigestAuth($header)
	{
		$temp = null;
		$data = array();

		// See ZF-1052. Detect invalid usernames instead of just returning a
		// 400 code.
		$ret = preg_match('/username="([^"]+)"/', $header, $temp);
		if (!$ret || empty($temp[1])
		|| !ctype_print($temp[1])
		|| strpos($temp[1], ':') !== false) {
			$data['username'] = '::invalid::';
		} else {
			$data['username'] = $temp[1];
		}
		$temp = null;

		$ret = preg_match('/realm="([^"]+)"/', $header, $temp);
		if (!$ret || empty($temp[1])) {
			return false;
		}
		if (!ctype_print($temp[1]) || strpos($temp[1], ':') !== false) {
			return false;
		} else {
			$data['realm'] = $temp[1];
		}
		$temp = null;

		$ret = preg_match('/nonce="([^"]+)"/', $header, $temp);
		if (!$ret || empty($temp[1])) {
			return false;
		}
		if (!ctype_xdigit($temp[1])) {
			return false;
		} else {
			$data['nonce'] = $temp[1];
		}
		$temp = null;

		$ret = preg_match('/uri="([^"]+)"/', $header, $temp);
		if (!$ret || empty($temp[1])) {
			return false;
		}
		// Section 3.2.2.5 in RFC 2617 says the authenticating server must
		// verify that the URI field in the Authorization header is for the
		// same resource requested in the Request Line.
		$rUri = @parse_url($this->_request->getRequestUri());
		$cUri = @parse_url($temp[1]);
		if (false === $rUri || false === $cUri) {
			return false;
		} else {
			// Make sure the path portion of both URIs is the same
			if ($rUri['path'] != $cUri['path']) {
				return false;
			}
			// Section 3.2.2.5 seems to suggest that the value of the URI
			// Authorization field should be made into an absolute URI if the
			// Request URI is absolute, but it's vague, and that's a bunch of
			// code I don't want to write right now.
			$data['uri'] = $temp[1];
		}
		$temp = null;

		$ret = preg_match('/response="([^"]+)"/', $header, $temp);
		if (!$ret || empty($temp[1])) {
			return false;
		}
		if (32 != strlen($temp[1]) || !ctype_xdigit($temp[1])) {
			return false;
		} else {
			$data['response'] = $temp[1];
		}
		$temp = null;

		// The spec says this should default to MD5 if omitted. OK, so how does
		// that square with the algo we send out in the WWW-Authenticate header,
		// if it can easily be overridden by the client?
		$ret = preg_match('/algorithm="?(' . $this->_algo . ')"?/', $header, $temp);
		if ($ret && !empty($temp[1])
		&& in_array($temp[1], $this->_supportedAlgos)) {
			$data['algorithm'] = $temp[1];
		} else {
			$data['algorithm'] = 'MD5';  // = $this->_algo; ?
		}
		$temp = null;

		// Not optional in this implementation
		$ret = preg_match('/cnonce="([^"]+)"/', $header, $temp);
		if (!$ret || empty($temp[1])) {
			return false;
		}
		if (!ctype_print($temp[1])) {
			return false;
		} else {
			$data['cnonce'] = $temp[1];
		}
		$temp = null;

		// If the server sent an opaque value, the client must send it back
		if ($this->_useOpaque) {
			$ret = preg_match('/opaque="([^"]+)"/', $header, $temp);
			if (!$ret || empty($temp[1])) {

				// Big surprise: IE isn't RFC 2617-compliant.
				if (false !== strpos($this->_request->getHeader('User-Agent'), 'MSIE')) {
					$temp[1] = '';
					$this->_ieNoOpaque = true;
				} else {
					return false;
				}
			}
			// This implementation only sends MD5 hex strings in the opaque value
			if (!$this->_ieNoOpaque &&
			(32 != strlen($temp[1]) || !ctype_xdigit($temp[1]))) {
				return false;
			} else {
				$data['opaque'] = $temp[1];
			}
			$temp = null;
		}

		// Not optional in this implementation, but must be one of the supported
		// qop types
		$ret = preg_match('/qop="?(' . implode('|', $this->_supportedQops) . ')"?/', $header, $temp);
		if (!$ret || empty($temp[1])) {
			return false;
		}
		if (!in_array($temp[1], $this->_supportedQops)) {
			return false;
		} else {
			$data['qop'] = $temp[1];
		}
		$temp = null;

		// Not optional in this implementation. The spec says this value
		// shouldn't be a quoted string, but apparently some implementations
		// quote it anyway. See ZF-1544.
		$ret = preg_match('/nc="?([0-9A-Fa-f]{8})"?/', $header, $temp);
		if (!$ret || empty($temp[1])) {
			return false;
		}
		if (8 != strlen($temp[1]) || !ctype_xdigit($temp[1])) {
			return false;
		} else {
			$data['nc'] = $temp[1];
		}
		$temp = null;

		return $data;
	}
}
